Musical instruments in the string family have a relatively softer tone than other instruments and consequently need amplification to match the output of other instruments in a band such as trumpet, sax, trombone and drum. This invention relates to an adjustable piezoelectric pickup that is secured on a string instrument bridge between a wing and a leg section. An adjustment is made to the original thickness of the pickup by sanding the flat wooden surface to the open dimension on the bridge beneath that wing section.
Sound pickup devices for stringed musical instruments have been typically air coupled devices, soundboard contact pickups and electromagnetic string motion detectors. The air coupled devices have the problem of sensing sounds from the environment other than the instrument itself. The contact pickups are limited in the quality of sound due to various deficiencies in reproducing the entire frequency range of the strings, which have multiple octave overtones and other frequencies. The magnetic pickups can only function with magnetic steel strings. Consequently a preferred type of device is the piezo-electric transducer for the stringed instrument family that can be wedge-mounted on the bridge of the instrument.
A type of this device is disclosed in U.S. Pat. No. 4,147,084 by Underwood. This pickup consists of a pair of pickups mounted between the legs and wings of the bridge of a bass viol. A brass case of slightly less than 4 mm ( 5/32 in.) contains a piezoelectric transducer for each device. This device will need a pair of shims to provide proper contact of both surfaces of the typically 5 or 6 mm gap that is on a standard bass viol bridge. This shim requirement is silent in the disclosure therefore removal of wood from the bridge would be required.
A second type of pickup is disclosed in U.S. Pat. No. 4,785,704 by Fishman in which a single pickup is mounted in the gap between the wing and the bridge of the violin family. Contact is maintained by an integral spring that will provide a snug fit in a violin for gaps between 1.3 and 2.3 mm (0.05 and 0.09 in.). The other instruments in the violin family, having a larger gap and therefore would require a shim to make a proper fit. On a banjo the pickup is mounted between the bridge and the body utilizing a separately manufactured spacer to maintain the proper fit. The pickup for a mandolin and guitar also requires a separate spacer. The upper and lower pickup surfaces of this device are of metallic copper and are part of the electrical signal transmission. Other methods of mounting electronic pickups on the string family require special bridge construction or modifications to a standard bridge which is undesirable for the end user of the instrument.
It is the purpose of this invention to provide an adjustable thickness pickup that can be inserted within the gap between the wing and leg of a typical string instrument bridge by an end user. The thickness of the pickup is carefully machined to be slightly larger than the standard gap of instruments in the violin family. The workable casing material, e.g. wood and soft plastic, is easily sanded by the owner to fit the instrument bridge gap. This device therefore avoids the need to modify the instrument bridge and also the need for separate and fitted shims as stated above in the prior art.